A single exterior French drain trench that’s 50 feet long means excavating about 75 cubic feet of soil. Depending on how wet your soil is (if you have a drainage problem, it’s probably pretty wet), that means 4 to 5 tons of dirt.
Not only do you have to dig out the dirt, you’ll have to move it somewhere. You’re going to refill your trench with gravel (another 4 to 5 tons), so the excavated dirt needs a new home, such as fill for a low spot on your property or a couple of raised garden beds.
Reality check: A French drain to cure soggy areas and minor flooding in your yard, sometimes called a curtain drain, can be a DIY undertaking. However, installing a footing drain to cure a wet basement is definitely a job for a pro.
Before doing any digging, contact your city services to mark the location of any underground utilities. Phone the Call Before You Dig hotline at 811. This free service makes sure underground utilities are marked before you begin. You can get additional information on digging services at Dig Safe.
Doing It Yourself
The good news is that digging your own trench by hand won’t cost you anything but time, plus what you’ll spend for drain pipe and gravel, a new shovel, and maybe a bottle of aspirin for the following day. If you can get a friend or two to help out, even better.
Costs for a hand-dug, 50-foot-long French drain, 12 inches wide, 18 inches deep:
- Planning: $0
- Excavation: $20 (new shovel)
- Plastic PVC drain pipe, 50 feet: $23
- Washed drainage gravel, 3 yards: $75; plus $40 delivery charge
- Landscape fabric, 3-by-50-foot roll: $40
- Grass seed: $10
Total costs: $208
Related: French Drains: When You Need Them
Renting a DIY Trenching Tool
A trenching tool cuts work time. You can knock off a trench that would take 6 hours to dig by hand in about an hour with a trenching tool. You’ll need to arrange a way to transport the tool to your property and back.
A gas-powered, walk-behind trenching tool will dig up to 18 inches deep and 24 inches wide. Expect to pay $125 to $200 per day.
Total costs (including materials, above): $313 to $388.
Renting a Backhoe and Operator
A backhoe is a major piece of equipment that will cut a trench quickly. However, to justify this tool, you’ll want to have plenty of work for it to do. A backhoe makes sense only if:
- You have more than 100 lineal ft. of drainage trench to dig.
- You can provide easy access to your property for this large piece of equipment.
- The backhoe won’t destroy landscaping features or compact soils irreparably. It’s heavy!
Including the rental fee for the tool, travel time to haul the backhoe to your property, and an hourly rate for the operator, expect to pay $300 to $1,500.
Total costs (including materials, above): $488 to $1,688.
Hiring a Professional
A professional contractor will complete your project for about $25 per lineal foot. That should include:
- An initial consultation and bid
- All parts and materials
- All labor
- Back filling the trench with topsoil
Total costs (50-ft. French drain): $1,250.
To find a pro contractor capable of building a French drain, search terms such as:
- Waterproofing contractor
- Basement contractor
- Drainage contractor
- Landscape contractor
Be sure your contractor is licensed and bonded.